Cylinder Head

When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

2.2L Engine

See Figure 1

Relieve the fuel system pressure.

Disconnect the negative battery cable.

Drain the cooling system into a suitable container.

Separate the air cleaner and air duct assembly from the vehicle.

Remove the lower air inlet.

Remove the serpentine drive belt.

Unsecure the alternator, and remove from the vehicle.

Remove the power steering pump, then position it aside without disconnecting the power steering lines.

Disconnect the spark plug wires, lay them aside.

Detach the control cables from the throttle body, then remove the cable bracket at the throttle body and valve cover.

When removing the valve train components, they must be kept in order for installation, in the same locations as they were removed from.

Remove the valve cover, rocker arm nuts, rocker arms and pushrods.

Disconnect the electrical harness from the intake manifold, throttle body and cylinder head.

Remove the O
2
sensor connection.

Unsecure the power steering pump bracket from the intake brace, located under the manifold.

Remove the torque strut and the engine side torque strut mounting bracket.

Tag and disconnect the vacuum lines at the intake manifold and cylinder head.

Disconnect the upper radiator hose from the engine.

Raise and safely support the vehicle.

Disconnect the exhaust pipe from the exhaust manifold.

Lower the vehicle.

Disconnect and cap the fuel lines at the quick disconnects.

Remove the transaxle fill tube.

Remove the cylinder head bolts.

Remove the cylinder head with both manifolds, then remove the intake and exhaust manifolds from the cylinder head.

To install:

Clean all the gasket surfaces completely. Clean the threads on the cylinder head bolts and the block threads.

Install the intake and exhaust manifolds on the cylinder head.

Place a new cylinder head gasket in position over the dowel pins on the block. Carefully guide the cylinder head into position.

Install the head bolts finger-tight. The long bolts go in bolts positions 1, 4, 5, 8, and 9. The short bolts are in the positions 2, 3, 6 and 7. The stud is in position 10.

Tighten the bolts in sequence. The long bolts to 23 ft. lbs. (32 Nm) and the short bolts and stud to 22 ft. lbs. (29 Nm). Make a second pass tightening the long bolts to 46 ft. lbs. (58 Nm). Maker a final pass over all the bolts tightening each an additional 100°.

Loosen all cylinder head bolts, then remove bolts and lift off the cylinder head.

With cylinder head on bench, remove all spark plugs for cleaning and to avoid damaging them during work on the head.

Installation is the reverse of removal. Clean all gasket surfaces thoroughly. Always use a new head gasket. The head gasket is installed with the bead downward. Coat the head bolt threads with heavy-bodied thread sealer. Tighten the head bolts in equal stages. Recheck head bolt torque after the engine has been warmed to operating temperature.

3.1L Engine (VIN T)

See Figure 6

LEFT SIDE

CAUTION

Care should be taken when working around the fuel system. DO NOT smoke or expose the fuel system to any flames or sparks. The fuel system is under pressure and must be relieved prior to performing any service work on the system components. Failure to properly bleed the system can lead to personal injury or component damage. Always keep a suitable fire extinguisher handy when servicing the fuel system.

Relieve the pressure in the fuel system before disconnecting any fuel line connections. Disconnect the fuel lines.

Disconnect the negative battery cable.

Remove the air cleaner assembly. Raise and safely support the vehicle.

Fuel Injection systems remain under pressure, even after the engine has been turned
OFF. The fuel system pressure must be relieved before disconnecting any fuel lines. Failure to do so may result in fire and/or personal injury.

Relieve the fuel system pressure.

Disconnect the negative battery cable.

Drain the cooling system.

Remove the top half of the air cleaner assembly and remove the throttle body air inlet duct.

Remove the exhaust crossover pipe heat shield and crossover pipe.

Disconnect the spark plug wires from spark plugs and wire looms and route the wires out of the way.

Remove the rocker arm covers.

Remove upper intake plenum and lower intake manifold.

Remove the left side exhaust manifold.

Remove oil level indicator tube.

When removing the valve train components they must be kept in order for installation in the same locations they were removed from.

Remove rocker arms nut, rocker arms, balls and pushrods.

Remove the cylinder head bolts evenly.

Remove the cylinder head.

To install:

Clean all the gasket surfaces completely. Clean the threads on the cylinder head bolts and block threads.

Place the gasket into position over the dowel pins, with the correct side facing up, if marked.

Coat the bolt threads with sealer and install finger-tight.

Tighten the cylinder head bolts in sequence to 33 ft. lbs. (45 Nm). With all the bolts tightened make a second pass tightening all the bolts an additional 90°.

Install the top half of the air cleaner assembly and the throttle body air inlet duct.

Connect negative battery cable.

Start vehicle and verify no leaks.

RIGHT SIDE (REAR)

CAUTION

Fuel Injection systems remain under pressure, even after the engine has been turned
OFF. The fuel system pressure must be relieved before disconnecting any fuel lines. Failure to do so may result in fire and/or personal injury.

Relieve the fuel system pressure.

Disconnect the negative battery cable.

Drain the cooling system.

Remove the top half of the air cleaner assembly and remove the throttle body air inlet duct.

Remove the exhaust crossover pipe heat shield and crossover pipe.

Raise and safely support the vehicle.

Disconnect the oxygen (O
2
) sensor connector.

Disconnect the exhaust pipe from the exhaust manifold.

Remove the right side exhaust manifold.

Lower the vehicle.

Disconnect the spark plug wires from spark plugs and wire looms and route the wires out of the way.

Remove the rocker arm covers.

Remove upper intake plenum and lower intake manifold.

When removing the valve train components they must be kept in order for installation in the same locations they were removed from.

Remove rocker arms nut, rocker arms, balls and pushrods.

Remove the cylinder head bolts evenly.

Remove the cylinder head.

To install:

Clean all the gasket surfaces completely. Clean the threads on the cylinder head bolts and block threads.

Place the gasket into position over the dowel pins, with the correct side facing up, if marked.

Coat the bolt threads with sealer and install finger-tight.

Tighten the cylinder head bolts in sequence to 33 ft. lbs. (45 Nm). With all the bolts tightened make a second pass tightening all the bolts an additional 90°.

Remove the ground strap from the rear cylinder head. Remove the fuel lines at the injector nozzles.

Remove rocker arm nuts, pivots, rocker arms and pushrods. Scribe pivots and keep rocker arms separated so they can be installed in their original locations.

Disconnect the exhaust crossover pipe from the exhaust manifold on the side being worked on and loosen it on the other.

Remove engine block drain plug, from side of the block where head is being removed.

Remove the plugs covering the upper cylinder head bolts.

Remove all the cylinder head bolts and remove the cylinder head.

If necessary to remove the prechamber, remove the glow plug and injection nozzle, then tap out with a small blunt
1
/
8
in. (3mm) drift. Do not use a tapered drift.

To install:

Install the cylinder head gaskets using a special composition gasket that must be used without a sealer.

Attach the cylinder head, head bolts, pipe thread plugs. Coat the plug threads, bolt threads and the area under the bolt heads with GM part no. 1052080 sealer or equivalent.

WARNING

Failure to coat the bolts with the correct sealer will result in coolant leaks and loss of clamping force on the cylinder head gasket due to thread and bolt-to-head friction. This will cause cylinder head damage.

Tighten the cylinder head bolts to:

Except No. 5, 6, 11, 12, 13 and 14 - 100 ft. lbs. (135 Nm)

No. 5, 6, 11, 12, 13 and 14 - 41 ft. lbs. (55 Nm)

Then retighten the cylinder head bolts to:

Except No. 5, 6, 11, 12, 13 and 14 - 142 ft. lbs. (193 Nm)

No. 5, 6, 11, 12, 13 and 14 - 59 ft. lbs. (80 Nm)

Fig. Fig. 9: Cylinder head bolt tightening sequence on 4.3L engines

Install the pipe thread plugs, install the plug so that the bottom of the plug is flush with the bottom of the hole to 0.250 in. (6.35mm) above.

Install the engine coolant drain plug.

Attach the engine crossover pipe to the vehicle.

Install the pushrods and rocker arms.

Bleed the valve lifters. Refer to the procedure outlined in this section.

Attach the ground strap.

Connect the glow plug wiring.

Install the fuel lines to injection nozzles.

Bolt on the oil level indicator tube.

Install the valve covers.

Install the intake manifold.

Fill the cooling system, start the vehicle, top off the coolant.

Check for leaks.

CLEANING & INSPECTION

See Figures 10 and 11

Chip carbon away from the valve heads, combustion chambers, and ports, using a chisel made of hardwood. Remove the remaining deposits with a stiff wire brush.

Fig. Fig. 10: Use a gasket scraper to remove the bulk of the old head gasket from the mating surface

DO NOT use a steel wire brush to clean an aluminum cylinder head. Special brushes are sold just for use on aluminum. Always wear eye protection when grinding chipping or wire brushing.

Be sure that the deposits are actually removed, rather than burnished. Have the cylinder head cleaned to remove grease, corrosion, and scale from the water passages. Clean the remaining cylinder head parts in an engine cleaning solvent. Do not remove the protective coating from the springs.

RESURFACING

See Figures 12 and 13

All machine work should be performed by a competent, professional machine shop.

Place a straightedge across the gasket surface of the cylinder head. Using feeler gauges, determine the clearance at the center of the straightedge. If warpage is between 0.002 in. (0.05mm) to 0.010 in. (0.25mm) in a 6 in. (152mm) span, or 0.004 in. (0.1mm) to 0.010 in. (0.25mm) over all, resurface the cylinder head. If warpage exceeds 0.010 in. (0.25mm) in a 6 in. (152mm) span, the cylinder head must be replaced.

Fig. Fig. 12: Check the cylinder head for warpage along the center using a straightedge and a feeler gauge

Fig. Fig. 13: Be sure to check for warpage across the cylinder head at both diagonals

If warpage exceeds the manufacturer's maximum tolerance for material removal, the cylinder head must be replaced. When milling the cylinder heads of V-type engines, the intake manifold mounting position is altered, and must be corrected by milling the manifold flange a proportionate amount.